Presently, most over-the-road vehicles are fuelled by gasoline or diesel fuel. There are certain shortcomings to using such fuels. They are increasingly expensive and they have an adverse impact on the environment because combustion products exhausted into the atmosphere are environmentally undesirable.
It is known that internal combustion engines can operate efficiently with reduced levels of pollutants in the engine exhaust if fuelled with natural gas or other combustible gaseous fuels, such as methane, propane, butane, hydrogen, and blends of such fuels. For vehicles fuelled with both gasoline and natural gas, for example, auxiliary fuel tanks filled with compressed natural gas (CNG) can be placed in the trunk or other storage areas of the vehicle and can be connected with the vehicle's fuel system for supplying fuel to the engine. Storing fuel in auxiliary fuel tanks on board a vehicle is limited by the available storage areas and in turn, the available fuel storage volume affects the distance that the vehicle can travel.
For pick-up trucks, auxiliary CNG tanks can be installed for example in the truck's bed. When installed in the truck bed, the auxiliary tank and its fittings are exposed to the surrounding environment and can be damaged by accidental impact caused by other objects carried in the truck bed or can be affected by exposure to adverse weather conditions. Also, when a CNG tank is installed in the truck bed this takes away space that can be used for carrying other objects, for example in a toolbox.
U.S. Pat. No. 6,039,203 describes a combination fuel tank/tool container for a vehicle comprising a container with a first compartment for holding a pressurized fuel and a second compartment for holding tools. In another embodiment described in the above patent the fuel tank/tool box combination comprises a fuel tank mounted on a mounting surface and a tool compartment supported by a wall provided with an opening for accessing the fuel tank gage and inlet. Alternatively, the tool compartment can be supported by both the wall and the fuel tank or just by the fuel tank itself.
An integrated fuel tank/tool box like the one described in U.S. Pat. No. 6,039,203 has the disadvantage that it is delivered to the customer as a unit which does not facilitate replacing parts that get damaged. The alternate embodiment described in the '203 patent, which comprises a tool compartment supported by the fuel tank or by a wall installed on the vehicle body, as illustrated, does not seem to provide a safe solution for installing a toolbox and a fuel tank on board of a vehicle since tool compartment is shown as being supported just by a vertical wall which would not provide enough stability.
With a unitary design the previously known solutions are not easily adaptable to different fuel tank specifications. A truck manufacturer may want to have the option of offering different sized CNG fuel tanks depending on the range requirements.
Accordingly, there is a need for an improved arrangement for protecting a fuel tank on a vehicle body while allowing some room for storage of other objects or loads that are carried by the vehicle. Preferably, the arrangement should be easy to install, while accommodating tanks of different dimensions and allowing the replacement of only the damaged parts without replacing the whole assembly.